In recent years, different types of radio networks have been developed to provide radio communication for various wireless terminals in different areas. The radio networks are constantly improved to provide better capacity, quality and coverage to meet the demands from subscribers using services and increasingly advanced terminals, such as smartphones and tablets, which often require considerable amounts of bandwidth and resources for data transport in the networks. Therefore, it is often a challenge to achieve good performance, e.g. in terms of high data throughput, low latency and low rate of dropped or lost data, in the radio communication between network nodes in the radio network and various wireless devices communicating with the network nodes.
In order to improve the performance of such radio communication, various radio network features can be employed that are intended to make the radio communication more efficient. For example, in radio networks operating according to Long Term Evolution, LTE, features such as Carrier Aggregation, CA, and Multiple Input Multiple Output, MIMO, are commonly used as defined by the third Generation Partnership Project, 3GPP. In carrier aggregation multiple carriers are used simultaneously in radio communication with a wireless device, while in MIMO multiple data streams are conveyed using multiple antenna ports at the sender node and at the receiver node. Carrier aggregation and MIMO are employed mainly to increase data throughput.
In the field of radio communication, the term “wireless device” is commonly used and will be used in this disclosure to represent any terminal or device capable of radio communication including receiving downlink signals transmitted from a network node and sending uplink signals to the network node. Throughout this disclosure, wireless device could e.g. be exchanged for User Equipment, UE, which is another common term in this field.
Further, the term “network node”, also commonly referred to as a base station, radio node, e-nodeB, eNB, etc., represents any node for radio access in a radio network that can communicate uplink and downlink radio signals with wireless devices. The radio network may also be referred to as a cellular network for radio communication. The network nodes described in this disclosure may, without limitation, include so-called macro nodes and low power nodes such as micro, pico, femto, Wifi and relay nodes, to mention some customary examples. Throughout this disclosure, network node could e.g. be exchanged for base station.
A radio network is typically supported and controlled by a network management system referred to as Operation and Maintenance, O&M, which may include various entities and nodes. A simplified example of a typical architecture for such a network management system is schematically illustrated in FIG. 1. In this figure, an O&M layer is indicated by a dashed box containing O&M nodes that observe how the radio network operates in radio communication with wireless devices, and also configure the radio network to operate with sufficiently high performance. The O&M layer may comprise a plurality of domain managers 100A, 100B . . . , each being connected to and communicating with a set of network nodes 104 of a particular domain.
In this example, only three network nodes, or base stations, 104 are shown connected to the domain manager 100A for simplicity, although a much greater number of network nodes may in practice be connected to each domain manager. The domain managers 100A, 100B . . . are in turn connected to a central network manager 102 which basically coordinates evaluation, operation and configuration of the radio network, which is well-known in this field. The network nodes 104 may perform performance measurements and report information about measurement results to its respective domain managers, which in turn determine how the network nodes should be configured, or re-configured, e.g. in order to improve the performance, based on the reported measurements.
In order to improve or maintain performance in a radio network, measurements of performance is obtained from the radio network on a more or less continuous basis, e.g. in order to detect and analyze any changes of performance occurring in the radio network. Such measurements may be obtained and provided from the base stations and/or other nodes in the network. As said above, it is of great importance that performance is maintained at a sufficiently high level which may be achieved by employing various radio network features such as CA and MIMO, whenever suitable and effective.
However, it is often difficult to know how efficient and helpful a particular radio network feature really is to the network performance, since many factors, apart from the feature itself, may impact the achieved performance at the same time. Therefore, it may not be possible to determine that a measured or otherwise detected performance improvement is the result of a newly introduced radio network feature or not, or how much impact the feature has had on the performance, and so forth. It is thus a problem to make a useful and reliable evaluation of the usage of a radio network feature in radio communication between wireless devices and a network node.